Hidden sector photons are weakly interacting, slim, hypothetical particles predicted by Standard Model extensions that have an extra U(1) gauge symmetry. Their only interaction with standard matter is a weak kinetic mixing with the photon. That is, photons can oscillate into hidden sector photons in a manner similar to that of neutrino oscillations; the probability or strength of this coupling is proportional to the kinetic mixing parameter, X. Ongoing experiments are searching for the hidden sector photon, and limiting X, over a wide range hidden sector photon masses. In this thesis we investigate and develop experimental methods to search for the hidden sector photon using microwave cavities, which typically probe a mass mγl ∼ 10 µeV. The archetype hidden sector photon experiment is 'light shining through a wall'. For microwaves, this consists of two isolated, resonance matched, microwave cavities, with ample shielding between them to act as a wall. Photons injected into one of the cavities are, by standard means, unable to propagate and produce a signal in the other cavity. If hidden sector photons exist, however, the photons in first (emitter) cavity are able to oscillate into hidden sector photons and travel through to the other cavity. Inside the second (detector) cavity, they can oscillate back into photons and be detected. The probability of this transmission has a strong dependence on the geometry of the cavity setup and excited cavity mode patterns. We investigate this dependence thoroughly and optimize the setup for axially stacked cylinders. The prototype experiment carried out in 2009 is also included for completeness. Building on this, we describe the follow-up light shining through a wall experiment currently under assembly.
|Publication status||Unpublished - 2012|